There is a lighting device for vehicles provided with a socket, and a light emitting unit including a light emitting diode (LED). The socket is provided with a flange, and a mounting unit provided on one face of the flange. The light emitting unit is provided at an end portion of the mounting unit, and the end portion of the mounting unit is inserted into a housing of a lighting tool for vehicles. In addition, an annular sealing member (gasket) is attached to a side face of the mounting unit. When the lighting device for vehicles is attached to the housing, the sealing member is interposed between the flange and the housing. For this reason, the inside of the housing is sealed with the sealing member. In addition, the flange and the lighting device for vehicles are supported by the sealing member.
Here, when setting an external dimension (sectional dimension) of the mounting unit to be small, it is possible to prevent the mounting unit which is inserted into the housing of the lighting tool for vehicles from standing out, when viewing the lighting device for vehicles from the outside of the lighting tool for vehicles. For this reason, it is possible to improve a design or a quality in appearance of the lighting tool for vehicles.
However, when the external dimension of the mounting unit is set to be small, also an external dimension of the sealing member becomes small. For this reason, a position of the sealing member which supports the flange moves to a center axis side of the lighting device for vehicles. As a result, a change in thickness of the sealing member which is formed of an elastic material has a remarkable influence on an inclination of the flange, and an inclination of the center axis of the lighting device for vehicles.
In this case, when simply using a sealing member with a large external dimension, a large gap occurs between the sealing member and a side face of the mounting unit, and a position of the sealing member is not fixed. When the position of the sealing member is not fixed, an inclination of the center axis of the lighting device for vehicles varies due to the position of the sealing member.
Therefore, it is desirable to develop a technology in which it is possible to suppress an inclination of the center axis of the lighting device for vehicles, even when the external dimension of the mounting unit is set to be small.